A 10-man Bayern Munich has ensured progression through to the knockout stages of the UEFA Champions League after piling on four goals against a lacklustre Olympiakos in the Bavarian capital.

The devastating display was over within 20 minutes after Douglas Costa, Robert Lewandowski and Thomas Mueller all got on the score sheet, with Kingsley Coman adding a fourth midway through the second half.

The reigning Greek champion struggled to get into the match, despite winning its preceding three group-stage matches, mustering 36 per cent possession and 11 less shots than the German side.

Olympiakos couldn’t take advantage of its extra man on the park, after Holger Badstuber fouled Ideye Brown in the 53rd minute, and must now manage a result against its next opponent – English side Arsenal – next month to ensure progression through to the knockout round of the competition.

Reds coach Marco Silva acknowledged his side wasn’t at the top of its game against the German giants.

“It is a heavy defeat but if you want to challenge such an amazing team you have to be the top of your game,” he said.

“We weren’t tonight. We did not fight as much as we should have. So we now have to get a result in our final game (against Arsenal).”

The Gunners managed a 3-nil home win against Dinamo Zagreb which leaves them three points behind Olympiakos. The two sides meet at Georgios Karaiskakis stadium on 10 December (AEDT) in a do-or-die clash for both clubs.